Cumana (Microdisc compatible) controller and I/O errors

[Hialmar]

Hi,

I have a Cumana controller which was built by Jean B. from CEO.

I have random I/O errors with it (for example, I have an error on a file, I reset the board and the error disappears).

Fabrice F. suggested it might be a Power problem. I use an ATX PSU from a PC. The board is powered through a classical IDE hard drive power connector and the disk drive by a classical disk power connector.

Here are some photos of the board and the setting.




On the CEO forums Didier (coco.oric here) suggested that I might need to power the Atmos with his own 9V PSU as well.

Is this risky for my Oric ?

Any other suggestions ?

Thanks a lot in advance,
Patrice

Edit: just in case someone wonders, the controller card bottom is protected with a card board (it is not in contact with the carpet).

[Chema]

I'm not a hardware guy, but I'd say DON'T power the Oric through its PSU AND through the expansion port SIMULTANEOUSLY. You risk damaging your Oric, the controller or both. Check first if the controller has some jumper to disconnect the power through expansion port.

I know some Orics have problems when being powered through the expansion port, and that might be your case indeed.

EDIT: I also think you don't have an AmpliBus card in the Oric expansion port (a card for 'cleaning' the signals). Most Orics need one to run properly with a disc controller (mine, for instance). That is why Cumulus has CumulsBus.

[Hialmar]

Thanks for your message.

I will ask Jean if there is such a jumper on the board.

About the amplibus, if you don't put it on your Atmos does it do the same kind of random I/O errors ?

[Chema]

In my case it is impossible to boot the OS. All I get is blocks onscreen when booting the Oric, maybe the "Insert system disc" message (sometimes corrupted), or random data in the first lines of the screen with a subsequent hang.

But as it is related to the quality of the bus signals (mainly the Phi2, but also all the rest including data and address lines) I guess anything can happen. I know some Orics even work without the amplibus.

[Dbug]

You could also try with a much shorter cable between the Oric and the board.

I know that on my old Cumana, just having the TV too close from the cable would make it impossible to load anything

[Hialmar]

Thank you for your advices.

I'll try to get a shorter cable and if I still have problems will try to build an ampli bus.

[Godzil]

The reason of the cumulubus for the cumulus is a bit more complex than on normal microdisc drivers, but yes you are right, it share some similar problems.

(One of the big problem the Cumulus have is by using "too much recent" part, it make more noise as expected on the IO/Lines)

For the original (including clones) microdisc, the more important stuff is the Phi2 potentiometer. It's hard to correctly set it, but an Amplibus shouldn't be necessary with a correctly set Phi2 Pot.

The Amplibus by cleaning the Phi2 signal (that the problem n°1 on the oric bus expansion) lower the need on a precise interpretation of the Phi2 in the microdisc hardware.

You should try to move slightly the potentiometer on you cumana board to find the correct position. Using an oscilloscope help a lot on this to get the correct timing, but it could be done without, it's just more difficult.

[Hialmar]

Thanks.

Fabrice gave me the same advice.

I'll try this ASAP.